Telephone system



L. A. MORTIMER.

TELEPHONE SYSTEM.

APPLICAYION FILED MAR. 2,1920.

1,406,678, Patented Feb.14, 1922.

, 5 SHEETS-SHEET l /f/,f/ aff/eee w L. A. MORTIMEH.

TELEPHONE SYSTEM.

APPLlcATloN FILED mm2, 1920.

1,406,678, muted Feb.. 14, 1922;

5 8 HEE1'S-SHEET 2.

ffy z am@ X NWN T @ARG/NAL L. A. MORTIMER.

TELEPHONE SYSTEM.

APPLICATION FILED MAR.2. 1920.

1,406,678. Patented Feb. 1411, 1922.

5 SHEETS-SHEET 3. @y J Uff/a@ x L. A.. MOHTIMER.

TELEPHONE SYSTEM.

APPLlcATxoN FILED MAR.2. 1920.

l ,406,678., Patented Feb. 14, 1922.

5 SHEETS-SHEET 4.

l: Wi?

NHL

+ -WJ -402 J' L. A. MORTIMERD' TELEPHONE SYSTEM.

APPucAHoN FILED MAR.2. i920.

1 ,406,678, Patented Feb. 14, 1922.

f/y Uff/ce2 HMG/NAL @MW/my i' nrrsn STATES LOUIS A. MORTIMER, 0F NEWYORK, N. Y., ASSINOR TO WESTERN ELECTRIC COM- PATENT OFFICE.

PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent. Patented Feb. 14, 1922.

Application filed March 2, 1920. Serial'No. 362,747.

T0 all whom it may conce/rn:

Be it known that I, LOUIS A. Mon'rrnnn, a citizen of the United States,residing at New York, in the county of New York and State of New York,have invented certain new and useful Improvements in Telephone Systems,of which the following is .a full, clear, concise, and exactdescription.

This invention relates to improvements in telephone systems and hasparticular reference to signaling, means employed with transmissionlines.

' Heretofore, it has been customary to em ploy physical and phantomlines for interconnecting distant ofiices. Selective signals have beentransmitted over these lines from one office to the other to controltelephone repeaters at intermediate ofiices andto signal operators atthe first named offices when connections are desired or when calls areterminated. It may sometimes occur, particularly when the jacks or otherterminals at the distant offices are multipled, that signaling impulsesare transmitted from the same or different othces simultaneously orcontemporaneously with the result that impulses may be lost.

An object of the present invention is to overcome the mentioneddifiiculty by providing' impulse storing means at yvarious oflices whichwill operate, when impulses are simultaneously transmitted, to storecertain impulses for sufiicient time to enable the others to betransmitted and then to releasel the stored impulses so that all of theirnpulses will successively perform their respective functions.

In the drawings, wherein the Iabove and other objects are realized.Figs. l to 5 inclusive, taken together and arranged side by side in themanner indicated by the circuit `lines extending to the margins of thedraw'- ings, illustrate what is now believed to be a preferredembodiment of the 1nvent1on. Fig. 6 is a diagrammatic view of a cordcircuit which may be used in connection with the invention.

Briefly, the invention is shown as consisti no part of the presentinvention it is deemed unnecessary to illustrate them in detail.

Each distant or terminating office is provided with an impulse mechanismcontainmg relays which are individual to each line terminating at saidoffice and upon the mltlation of a call on one of the li'nes the relaysassociated therewith are operated to establish an'impulse circuit whichtransmits an lmpulse to the nearest intermediate office where the sameis repeated and again transmitted until it reaches the other distantoffice. The passage of the impulse through the intermediate oflices isutilized to render effective the telephone repeaters thereat. At saidother distant office the impulse actuates mechanism individual to theparticular line over which the call is initiated to inform the operatorthatthe line has been taken for use. Preferably, the physical lines Aand C are employed for the transmissionrof the various impulses andnormally included with these lines'at the vari ous offices are relaysresponsive tti-differenti` polaritles of `current so as to identify the"particular line over which a call is'initat'ed. Upon the removal of'allplugs from the jacks at the terminating offices, impulses of a differentcharacter from those utilized in' establishinoconnections aretransmitted from the distant oflices to restore the tele phone repeatersto normal.

The mecha,sm at the two distant offices is arranged so that, in theeventof simul taneous or contemporaneous calls being initiated at thesame ofiiee, the same will operate to immediately transmit the impulsefor one of the calls and to store the other impulse until the first hasbeen transmitted whereuponthe mechanism again operates to send thesecond'impulse. The mechanism will operate in a like manner should anincomingimpulse reach a distant office at the same time that a call isinitiated thercat. For simultaneous impulses transmitted from differentoflices and meeting: therebetween.y

an impulse storing,r mechanism is provided at the intermediate ofiice Xwhich lstores the first impulse received thereat until the secondimpulse has passed through whereupon said first impulse is transmittedfrom said oiiice.

ll'ith' this general description in mind, it is believed that theinvention will now be 'fully understood from the following,f detaileddescription of the operation.

fes

the physical line `lays 22 and 51.

Operator at oyce W initiates a fc5/F3 to. ao@ Z over' Zine A.

rlhe operator at olice `W desiring to initiate a call over line A.inserts the plug in a circuit extending from ground through its middlealternate contact and vWinding, the sleeve contacts of jack 20 and theplug or the link circuit to grounded battery. Relay 21, upon energizing,immediately opens the circuit for relay 22, but this relay being slow torelease maintains the alternate 'contact thereof closed for a suilicientlength of time to transmit a signaling impulse. rl`he energization ofrelay 22 establishes an impulse circuit extending from grounded batterythrough the alternate contact of relay 22, the right-hand winding ofrelay 51 and the winding of slow-to-release relayv .52 t'o ground; Therelays 51 and 52 energize in this circuit, relay 51 maintaining'itsalternate contacts closedduring the energization of relay 22. Relay 52,being slow to release, will Vmaintain itsalternate contacts closed for aperiod of time after the release of vryerl`he closure ofthe alternatecontacts of -relay 52 establishes short 'circuits for slow-to-releaserelays 54, 56 and 58 to prevent energization of these `relays during thetransmission of the impulse from oilice W Jfor line A. The `energizationor relay 51 establishes a circuit extending from grounded batterythrough the Anormal contact of relay 3, the winding o t relay 4 and' theouter left-hand alternate contact or relay 51 to ground. Relay 4energizes in this circuit and disconnects the polar relays'1 and 2 andrelay v3 from the simplex conductors included in the physical linesextending between oiiceslV and X. The energiza-` tion of relay 51 alsoestablishes an impulse circuit extending from the negative pole ofbattery 62, preferably of 60 volts, through the outer right-handalternate contact of relay 51, the right-hand normal contact oi. relay61, the right-hand normal Contact of relay 60, the upper alternatecontact of relay 4, the simplex conductors included in thev physicalline C extending between office and the mechanism of oflice X shown 1nFig.

2, the upper normal contact of relay 202, the l windings of relay 203and thepolarrelays 200 and 201, the lower normal contact of relay 202,the simplex conductors included in A extendinlgbetween ,the

-cuit and establishes an vobvious energizing l upper-contact of polarrelay 201 establishes Arelay 320 is inceste mechanism at ofice X shownin Fig. 2vand oiice WV, the lowerv alternate contact of rel lay 4` theleft-hand normal contact of relay 60, the left-hand normal/il contact ofrelay 61,

and the inner right-hand alternate. contact of relay 51 to the positivepole of battery 62.-

At the termination of the impulse extending over this circuit,relaysi'22 and 51rrelease and the release of the latter relay opens thepreviously described circuit for relay 4 which then restores to normal.lThe release or relay 22.establishes a circuit extending trom groundedbattery through the right?- hand alternate contactof relay 21', thenormal contact of relay 22 and the winding of slow-'to-release relay 23to ground. Relay 23 energizes and remains in this condition as long as aplug is inserted into yjack 20, but the energization of-relay 23 at thistime has no effect upon the system. After-.the 'termination of theimpulse, relay 52 remains, energized for.A a definite interval and thenre,

leases to open the 'shunt circuits for relays 54,56 and 58'.

The strength and fdirecti'on of How of the current in the impulsecircuit passingv through relays 200, 201 and 203 is such as to cause theenergization of polar relay `2.01 which in this instance closes .itsupper vcontact. Relay 203 is also energized in this circircuit forslow-to-release relay- 214 but the energization of this relay at thistime has no eiiect upon the system. The closure of the a circuitextending from grounded battery, through the resistance'212, the uppercontact of relay 201 and the windings of relays 204 and 205 to ground.Relay 205 is marginal and does not energize i-n this circuit due to theinclusion of the resistance 212, but relay 204 energizes to establish anobvious circuit for tilarnentcontrol relay 319. This relay .energizesand locks in a circuit extending from grounded battery through itswinding and contact and the contact of relay -320 toground. Theenergization of relay 319 connects battery through its lefthandalternate Contact to1 the filaments of telephone repeatersconventionally.. illustrated at RA and RC associated with lines A and Crespectively to render said repeatvvers effective. Relay 319 remainsenergized as long as a plug is inserted into any one of the jacks atthe-terminating oflices lV and 15 Z, but when all of these plugs areremoved energized in a manner to a'ppear in the course -of -thedescription to` open the locking circuit for relay 319 and thusremove-the battery supply.` from the ila- 1i ments of the telephonerepeaters.

rlheenergization of relay 204 also establishes a circuitfextending Vfromgrounded battery through the normal contactsof relays 207, 206', and 205'in series, the lower 11 'relay 302 and the middle right-hand contact ofrelay 351 to ground. Relay 302 energizes and disconnects the polarrelays 300 and 301 and relay 303 from the simplex conductors included inthe lines A and C at ofiice X. The energization of relays 302,

. 351and 361 establishes an impulse circuit extending from the positivepole of battery V362, through the outer left-hand contact of relay 351,the left-hand alternate contact of relay 361, the right-hand normalcontact of relay 360, the upper alternate contact of relayv 302, thesimplex conductors included in the physical line C extending betweenofiice X and ofiice Y, the upper normal contact of relays 404 and 405.the middle normal contact of relay 406, the upper normal contact ofrelay 407, the winding of relay 408, the windings of polar relays '401and 400, the middle lnormal Contact oi' relay 407, the lower normalcontacts of relays 406, 405 and 404, the simplex conductors included inline A extending between oflices Y and X, the lower alternate contact ofrelay 302, the left-hand normal contact of relay 360, the right-handalternate contact of relay 361, the inner left-hand Contact of' relay351 and the resistance 364 to the negative pole of battery 362. At thetermi.-

nation of the impulse relays 302, 351 and 361 release. The direction andstrength of:l :flow of current in the circuit just described does notaffect polar relay 401, but causes the polar relay 400 to close itsleft-hand contact whereupon a circuit will be established from groundedbattery through the resistance 415, lett-hand Contact of" polar relay400 and the windings .of relays 409 and 410 to ground at the contact ofrelay 413. Relay 409, being marginal, does not respond to the currentflowing through this circuit but relay 410l -energizes and closes itsalternate contacts.

A circuit will then be established from ground through the outer upperalternate vcontact of relay'410 and the winding of rey lay 41.9 togrounded battery. Relay 419 energizes and establishes a locking circuitfor itself extending from grounded battery throu h the winding andright-hand contact' of said relay and the contact of relay 420 toIground.A In energizing, relay419 connects battery iff. its left-handcontact and this bat-v tery is extended to the filaments of theteleground.

pear in the course of the description, which occurs when allfof' theplugs are removed y lfrom the jacks at the two dlstant offices.

The current previously referred to, which flows through polar relays 400and 401, also energizes relay 408 and removes ground from the contactthereof to prevent the operation of any ot' the relays 404, 405, 406 and407 during the transmission of the impulse to oflice Z so that animpulse tranmitted from the latter oflice duringtliis interval will haveno effect upon said relays.

The energizat-ion of relay 410, under the control of polar relay 400.establishes a circuit extending from the positive pole et battery 418through the lower alternate contact of relay 410, the lower normalcontact of relay 409. the simplex conductors included in the physicallineA extending between office Y and office Z, the lower normal Contactof relay 502, the windings of polar relays 501 and 500, the winding ofrelay 503, the upper normal contact of re- .lay 502, the simplexconductors included in the physical line C extending between office Zand office Y, the upper normal contact of` relay 409, the inner upperalternate contact ot' relay 410` the upper normal contact ot relay 412and the resistance 421 to the negative pole of battery 413. The strengthand direction of flow of current in this circuit has no effect uponpolar relay 500. but causes polar relay 501 to close its upper contact.Relay 503 also energizes in this circuit and establishes an obviousenergizing circuit for relay 514` but the operation of this latter relayhas no effect. upon the system at this time. The closure of' the uppercontact of polar relay 501 establishes a circuit extending from groundedbattery through resistance 512, the upper Contact of relay 501 and thewindings of relays 504 and 505 to Relay 5.05, being marginal, does notrespond to the current fiowing in this circuit but relay 504 energizes.A circuit is tlhereupon established extending from grounded batterythrough `the normal contacts of relays 507, 506.and 505 in series, thealternate contact of relay 504 and the lower winding of relay 508 toground. Relay 503 energizes and locks in a circuit extending from groundthrough the, upper winding and the contact of said relay, and the middleleft-hand normal contact of relay 521- to grounded battery. By closingits contact, relay 508 also establishes a circuit from ground throughlamp 515, the right-hand, normal contact of relay 521. the (Xmtact ofrelay 508, and the middle lefthand normal contact of relay 521 to grounded loL eryllana-.p filo is lighted in this circuiis'and the operator atolliee iii oloseiving the eondition of "this lain@ inserts the plug Z0oil? another linli eireuitinto jack 520. This operation estalhlishes aoirM cuit extending from e ounded battery at the linlt circuit through'the winding;n of relay l 1 the sleeve contacts ot' 'the plug ol' saidcircuit and the jack 520., 'lhe Windingl and inner left-hand normalContact ot relay 521 and the wheeling oi? slow-to-re lease relay toground lllelay T1 ener- `gilles hut has no effect` upon the linkeircuit. Relays 521 and energize and the energization of the formeropens the pre yiously described circuit- 'lior lainp 515 which lamp isthereupon extinguished. Relay 521 locks through its finding and. middlealternate Contact to ground l in energizing opens the circuit. tri' hayl being;- slow to release. however. does not open its alternate Contactuntil after va definite period of tiine has elapsed and during this timean impulse is Vtransinitted 'lfroni officie `Upon the release et saidrelayfJ re lay 523 is energized through the normal Contact of relay andthe outer leitliand alternate Contact oi relay 521. rlhe circuit forthis impulse exends 'troni grounded hat tery. through the alternateContact el' relay the helft-hand Winding; ol ro-lay i and the Windin` ofslow-to-release relay 0:52 to ground. Relays and energize and theenergization of the latter relay in Closing its alternate contant/Sestablishes shunt circuits for slou'to-release relays Soll, v550, and toprevent the energiaation thereof during the. transmission ot thevimpulse. rlhe energization of relay :351 establishes circuit extending`-lironi Igrounihi,d battery through the norinal Contact of relay 503,the Winding of relay 502 and the outer right-hand alternate Contact ofrelay 551 toY `ground. Relay 502 energizes and disconnects polar relay503 Afrom the simplen conductors included in the yilhysieal lines atoilice f. The energization of relay 551 establishes an irapulse circuitext-ending 'from lhe negative ole of hat-tory through the outer lel;lland contant ol relay 551. the left-hand nor mal oontacls oli relays501 and 500. the up per alternate rontaet ol relay 500. the sini plexconductors included in 'the physical line C extendingy between oiliieand oilice Y. the upper normal contarte of relays 409, 410, 411 and themiddle normal Contact oil relay i12, the Windingol' relay 13, thewindings of polar relays 402 and 03, the vlower normal Contact ot' relayLi12, the middle normal oonaet-f relay L211. the lower normal' contact-solf' relays `ell0 and 09, the simplen crmductors included in thephysicalline .Ki eiitendis' lietween o'ee Y and ernale oimlaet of relay if?.This relayI relays 500 and 501 and tht- 502, the lays 500 a Contact olrelay lo the 1piisitiye pole or elal/ h3 energazes in this removingground from its Contact prei/ents ,ne energiaation any one oi' therelays j l0 Llll and. e194 during i ion oithe impulse -rona oiiice ouehL Hoym i. 11a r .i Gly 19H ,i .e i reet-ion el: low and stienei o1 @ne75.

tate o" relay 08 to ground. Relay 40e7 heincf marginal., does noi',respond to the Dourrentowing "Qhrough this cireuit,lnit relay 8 405ooerates close its alternate contacts. m l f ille closure oit allelowerinost, alternate contact oi relay Ll05 establishes an energizingcire-uit for relay 19, loutJ as this relay is alreaoy energized andlocked to supply loat- 9 #ery to 'the i'ilaments olf the telephonereeaters at onine Y the closure ot the Circuit for relay e119 hy theenergization of relay Ll05 lv no effect upon the oriner relay. v

rlhe energization of relay 405 under 'the 9 control of polar relayestahlishes an iinoulse circuit extending iron). the positive pole oil4hattery L110, through the uppermostv alternate Contact of relay 105,the upper normal Contact of relay 40%, the simplex` con- 100 duetorsincluded in line C extending between office and oilice X, the upperlnormal Contact of relay 302, the Winding of relay 303, the windings oipolar relays 300 and 301,

she .lower normal Contact. of relay 302, 'the 105 simplen conductorsincluded in line A. extending between oihee and office Y, the lowernormal cont-act oll relay 404C, 'the inner lower alternate Contact ofrelay 405, the

lower normal. Contana o relay and the resistance lill to the negaibivenoloi`\= hat tery The relay 303 energi'zes in this circuit andestalolishes an obvious energizing Y circuit :tor slorwtoa'elease relay3li, hut -tlie energization o' the syslern at this time. rllhe strengthand directie ol liow of the current in the cireuit nding Vthrough polarrelays 300 and 301 causes 'the latter relay to close its lowerconta/cl3, :from grounded battery through the resistance 312, .lowerContactl of relay 301 and the windings oi' relays B051A and 305 'toground. Relay 305j heling marginal. does not respond to 'the currentllowing in this circuit due to 125 the resistance E312, but relay 304eenergizes and estahlishes an obvious energizing circuit 'for relay Thisrelay is already ener-v giaedand looted, and therefore the establishofthe new energizing circuit 1a'li,: .reiipon a circuit is established 120for the 13G this relay has no effect upon' 115 same, .has no etlect. Theenergization of relay 304 also establishes a circuit extendin fromgrounded battery through the normagl contacts of relays 307, 806, and305 in series, the lower alternate contact of relay 304, and theright-hand Winding ot' relay 251 to Iound. Relay 251 energizes in thiscircuit and establishes an energizing circuit for relay .202 extendingfrom grounded battery, through the normal contact ot relay i203, Windingof relay 202 and the middle letthand contactot' relay 251 to ground. Theenergization of relay 251 also establishes a circuit extending fromgrounded battery through the winding of relay E259 and the outerleft-hand contact ot' relay 251 to ground. Relays 202 and 259 areenergized and the energization of the former rela disconnects the polarrelays 200 and 201 from the conductors included in the physical lines AAand C at oiice X. Therefore, upon the energization of relays 202, 251and 259, an impulse circuit is established from the posin tive pole ofbattery Q62, through the outer right-hand contact ot' relay 251,right-bami alternate Contact of relay 259, the right-hand normal contactof relay 260, Vlower alternate contact of relay 202, the simplexconductors included in the line A extending between Fig. 2 and Fig. 1,the lower normal contact of relay 4t, windings ot polar relays 1 and 2,winding ot relay 3, upper normal contact ot' relay 4, the simplexconductors included in line C extending between Fig. 1 and Fig. Q, upperalternate contact ot' relay Q02, letthand normal contact ot relay 260,left-hand alternate contact of relay 2,59, inner righthand contact ot'relay 251, and resistance 264 to the negative pole ot battery 262. Relay3 is energized in this circuit to establish an obvious energizingcircuit 'for slow-torelease relay 14, but the operationf ot this latterrelay has no effect upon the circuit at this time.

The strength and direction o'l flow ot' current in the impulse circuitjust described has no effect upon polar relay 2, but cause the polarrelay 1 to close its uppcr contact. A circuit is then establishedextendingfrom grounded battery, through the resistance 12, the uppercontact of polar relay 1 and the -Windings ot' relays 5 and 6 to'ground. Rela y 6, being marginal, does not respond to current flowing inthis circuit, but relay 5 op'erates to close its contact. A circuit isnow established extending from grounded battery, through the normalcontacts o'l relays R, T and 6 in series, the contact ot' relay .i andthe lower winding of relay 9 to ground. Relay 21., being energized, theupper winding ot relay 9 is short circuited by the ground at theleft-hand alternate contact ot relay 21. Relay 9 is energized by thecircuit just described for it, but due to the short circuit,

this relay will not lock through its winding and contact and thereforewill remain energized only throughout the duration of the impulse.Encrgization of relay 9 establishes a circuit `for relay 25, which isnormally shortcircuited through the middle righthandynormal contact otrelay 21. extending from grounded battery through the winding ot' relay25, the contact of relay 9 and the lett-hand alternate contact' ot relay21 to' ground. Relay 25 energizes and in so doing connects a` source ofsignaling current to 'the line and link circuit. which will give amomentary audible signal to the operator at ofiice lV whose listeningkey 7 is actuated at this time to indicate that the ope 'ator at oiliceZ has responded by inserting a plug into jack 520.

At the termination of the conversation on line A the operator at oice lVmay transmit a disconnectsignal to the operator at office Z, or duringthe useot line A may re-ring the operator at the ringing key (not shown)of the link cir- .cuit connected to ]ack Q0 whereupon a circuit will beestablished for relay 24 extending from a sourceo'f signaling current(not shown) through the tip contacts of the plug 70, jack 20 and thelett-hand normal contact ot relay E25. the winding oi relay 24. the lefthand winding of the repeating coil adjacent the latter relay. theright-hand normal contact oi relay 25 and th'c ring contacts of jack 20and )lug T0 to ground at said ring ing key. Relay 24 energizes andestablishes an impulse circuit extending from grounded battery throughthe right-hand alternate contact ot' relay 21, the normal contact ofrelay 22 and the lett-haml contact of relay where it joins the circuitpreviously traced for rclays 51 and 52. The closure of the right-handcontact ot relay .24 short circuits line A and prevents the transmissionell the signaling current thereovcr to oce Xi Relays 51 and 52 operateto cause the trans'- mission ol an impulse trom' oilice lV through thevarious olices as previously described. resulting in the energizationot' relay 008 at oflice Z. Due to the energization of relay 591. at thistime, the upper winding of relay 508 is shunted by the ground at therighthand alternate contact of relay 521 and therefore relay 508 willnot lock through its upper winding and Contact, but will remainenergized only throughout the duration of the impulse. Operation otrelay 508 establishes a circuit Jfor relay extending from' groundedbattery, through the winding of said relay, the contact-ot relay 508,and the righteliand alternate co'ntact of relay 521 to ground. Relayenergzes and connects a. source of signaling current 526 to the linkcircuit.engaged with jack the right-hand winding of the bridged relay 73which thereupon energizes to establish a locking circuit extending frombattery' the latter office by actuating 5:20 and through y iso l herlistening lrey to ascertain the nature of' Frs Q12) 'through therightdiand Contact oi key 72, the contact and lett-hand Winding of relay73, the contact of relay 'T1 and the lamp 7l to ground. Lamp 'la islighted in this circuitandthe operator observing the same, actuates thecall and by so doing opens said locking circuit and extinguishes :thelamp lai. lt the signal be .tor disconnect. the plug is then Withdrawnfrom jack 520 and relays 521 and 523 release. Release ot relay 523 willhave no effect upon the system at this timeu it it be assumed that linesB and C are in use and relays 531 and 541 are energized.

. ln the same mannerfthe operator at oilice Z'inay transmit a disconnectsignal to the operator at oi'lice lll by operating the ringing lrey ofthe link circuit connected to jack 520 whereupon relay 524: will beoperated over an obvious: circuit by' asource of signaling currentassociated with said link circuit. The closure ot' the lett-hand contactot relay 52st short circuits the line A, and prevents the passage ot thesiglnaling current over said line to oiiice Y. The closure ot theright-hand vContact ot re- .lary 524- establishes an impulse circuit ex-'manner as previously described.

tending from grounded battery through the lett-hand alternate contactotf'relayf521, the normal contact ot relay 522 andltherighthand Contactot relay 52eL mille-'refillt joins the previously traced circuittorjfrelays and 'lhese relays operate :inthe sarnemanotlice Z throughthe various 'otheirofllices to operate relay 9.Vv This relay 'alsohas'fits up- `per Winding short circuite'd liv thieuground at thelett-hand alternate Contact'oi1 relay 21., and therefore only remainsenergized Ythrouglriout the durationof the impulse. @neral-ion ot relay9 establishes a circuit ,to-r relay extending tromv grounded bat' terythrough the Winding loit said relay. vthe contact ot relay 9 and thelett-hand alternate Contact oi"I relay 21 to ground. ln energizing relay25 connects the source otlsignaling current 26 to the link circuit tolight the lamp 'la associated therewith in the same Receiving thissignal, the operator may then remove the plug 7 0 of thelink circuitfrom jack 20 whereupon relays 21 and 23 release. The release of relays21 and 23 vwill have no effect upon the system it it be assumed thateither' oi" .lines B and C or both are in use and relays 31 and i1 lreptenergized by the plugs engaged with jacks 30 and 10. f at 077%@ Winitiates a @all to oyoe Z over Zia-e B.

The operator at oiiice lV desiring a c0nnection to otlice Z over line Binserts a plug Operator T0 ot another link circuit into jack 30 and`thereby establishes a circuit extending from grounded battery through4the Winding Of i ,andere relay 71, 'the sleeve contacts ot the plug ofsaid circuit and jack v30, the winding and inner right-hand normalcontact of relay 31, the Winding of sloW-to-release relay 32 to ground.Relay 31 energizes and locks through its winding and middle alternatecontact to. ground and by energizing opens a circuit for relay 32 Which,being slow-t0-v release, does not open its alternate Contact until aftera period of time has elapsed sufiicient to transmit an impulse fromoiiice W. The energization of relay 32 establishes an impulse circuitextending 'from grounded battery, through the alternate contact of relay32, the left-hand Winding of relay 53 and the winding otsloW-'to-releaserelay 54' Relays 53 and 54 energize and left-handnorraacontact of relay 52 to' ground. The energization of relays el, 53and 61 establishes a circuit extending from 'the negative pole ofbattery 62, through the outer left-hand alternate contact oi relay thelett-hand alternate contact of relay 01, theleft-hand normal Contact ofrelay'60, the 'lower alternate contact of relay 4,the simplex conductorsincluded in the physical line extending between office W and themechanism of otlice X shown in Fig. 2, the lower normal contact ot relay202, windings of polar relays 201 and 200, the Winding of relay 203,upper normal contact 0i relay 202, the simplex. conductors included inthe physical line C extending between Fig. 2

and Fig. 1, the upper alternate contact of contact ot' relay 32, and theright-hand all ternate contact ot'l relay 31 to grounded battery. rlheenergization of relay 33 at this time has no ei'ect upon the systemsince relays 21 and 31 are both energized. Relay 203 is energized inthel impulse circuit'to esta-b'-4 lish' an obvious energizing circuitfor relay 21a but the operation of the relay at this time has ne @Eenupon the system, The strength and direction ot' flow ot' the currentthrough polar relays 201 and 200 is such as to cause the former relay toclose its lower contact. A circuit is then established extending fromgrounded battery, through the lower contact ot relay 201 and thewindings ot relays 204 and 205 to ground. Since the resistance 212 isnot included in this circuit. relays 204 and 205 will both energize andthe operation ot' the former relay again establishes the originalenergizing circuit for relay 319. but inasmuch as this relay is alreadyin a locked condition to supply battery to the tilaments ot telephonerepeaters RA and RC. theestablishment of the last energizing circuit forsaid relay has no effect thereupon. 'lheenergization of relay 205establishes a circuit extending from grounded battery. through thenormal contacts of relays 20T and 206, the alternate contact of relay205, and the right-hand winding of relay 353 to ground. Relay 353energizes to establish an energizing circuit Yfor relay 302 extendingfrom ground through ythe outer lett-hand contact ot relay 353, thewinding ot' relay 302, and normal contact of relay 303 to groundedbattery. The energization ot' relay 353 also establishes an impulsecircuit extending from the positive lpole ot' battery 302 through theouter right-hand contact of relay 353, the righthand normal contactot`relay 5501. the lett-hand normal contact oiZ 4relay 300, the loweralternate contact of relay 302, the simplex conductors included in lineA extending between ofiice X and office Y. the lower normal contacts otrelays 404, 405 and 406, the middle normal contact ot relay 407, thewindings of polar relays 400 and 401, the winding of relay 408, theupper normal contact ot relay 407. the middle normal contact of relay406, the upper normal contacts of relays 405 and 404, the simplexconductors included in the line C extending between olice Y and ofliceX, the upperl alternate contact ot relay 302,- thc rightehand normalcontact of relay 360, the lett-hand normal contact ot' relay 361. theinner ri`ght-hand contact ot' relay 353 and the. resistance 364 to thenegative pole of battery 362. The strength and direction of How ot'current in this circuit again energizes relay 408A to remove ground fromits contaccto prevent the operation of any ot thc relays 404. 405, 40Gand 40T during the transmission of the impulse. The polar relay 401 doesnot respond to the current flowing in this circuit but relay 400operates to close its right-hand contact. is thereupon established tromgrounded battery through the right-hand contact of relay 400 and thewindings of relays 409 and 41.0 to ground at the contact of relay 413.Since the resistance 415 is not included in this circuit, both relays409 and `410 wlll energize and in the closing of the outer up- A circuitper alternate contact. of relay 410` ground will again be connected tothe winding ot' relay 419. but this relay being already energized audlocked the circuit therefor will have no ell'ect upon the relay and thebattery supply to the tlamcnts ot' the telephone repeaters BA1 and RC1will not be atlccted.

The encrgiza'tion of relays 409 and 410 establishes a circuit extendingfrom the positive pole of battery 418 through the middle alternatecontact ot relay 409, the simplex conductors included in physical line Cextending between ollice Y and otiice Z. the upper normal contact ofrelay 502, the winding of relay 503` the windings of polar relays-500and 501. the lower normal contact of relay 502. the simplex conductorsincluded in physical line A extendingbetween oflice Z and ofiice Y, thelower alternate contact of relay 409, the lower normal contact ofV relay411 and the resistance 421 to the negative pole of battery 418. Relay503 responds to current flowing through this circuit and establishes thepreviously mentioned circuit for relay 514. but the energizintion ot'this relay, at this time. has no effect upon the system. The strengthand direction ot' flow ot' the current from battery 418, in thisinstance. has no cfl'ect upon polar relay 500 but causes polar relay 501to energize and close its lower contact whereupon a circuit isestablished from grounded battery through the lower contact of polarrelay 501 and the windings ot' relays 504 and 505 to ground. notVincluded in this circuit. both of the relays 504 and '505I willenergize. A circuit will thereupon be established from grounded batterythrough the normal contacts of rei lays 507 and 506, the alternatecontact of relay 505 and the lower winding of relay 509 to ground. Relay509 energizes and locks in a circuit extending trom ground through thewinding and contact ot said re' lay and the middle lett-hand normalcontact of relay 581 to grounded battery. The energization of relay 508establishes a circuit extending from ground through the lamp 517individual to line B, the right-hand normal contact of relay 531, thecontact of relay 509 to grounded battery at the middle lefthand normalcontact of relay 531. The circuit extending through the' lamp 517 lightsthe same and the operator at oflice Z observing the lighted condition ofthe lamp inserts the plug 70 of another' link circuit into the jack Theengagement of the plug with 'ack 530 establishes a circuit through thesl eve contacts of the plug of said circuit and jack 530. the windingand inner left-hand normal contact of relay 531 and the winding ofslow-to-release relay 532 to ground. Relays 531 and 532 energize and theenergization of the former opens the previously described inasmuch asthe resistance 512 lis circuit. for the lmnp 517 which is lierenpon .ofrelev 50:2, the

exiin v'uielierl.

Relay 531 locke through its winding anal middle alternate conteeo toground and in energizing opens z-he circuit for relay This relay beingSlow to -relese7 however, does nory open its alternare eonieci untilafter :L rierinite period of linie nee elapsed which is Snflicieni totransmit en impulse roin oiliee ,Z ljpon alle rerease of reloj! at lieend of the iingnileey 533 energizes ilirongli 'the normal ci@ of relayund the outer le-liancl fren nnte eoneei of relu?,T 525i. This impulseis proiliicefl oy cireui extending from grounrlerl liziiery lirongli"cire alterniiie oon ceci of relay 2, ne rigli-liend Winning of relay553 incl lie winding; or' elowiorelea-se relay 5511i to ground. Relaysand. 554i energize nnfl il'ie energizetion ol the le 'ier reluj;enaniislies slniin eirei' rougir its alternate coni; f

lense relays i So that liese laer relays 'will noi be energized hiringAalie ronsmission oiE the impulse from oilice Z. The ei'iergization offrelay establishes 2r 556 :rml Y .zi circuit extending from groundedlietery rlirongfli the normal confusi of relayr 503, the ,vinoini" olireil,7 502 :incl lli-e outer le'i'biienrl x n .WLI L l.,l: 01p r v10 .in0.,.

. OikrdCL ai in@ do i, .OIOLUN Relay 5502 encrgizee und disconneele'shire polar relays 500 and 50i i Aelan 503 'from ine conrinororeeonneorecl i l linee it oince Z. 'iie eiiergfiziiiori of relay elmoeeiablielies e eireriiry for relai; Sei

exiendino from grounclecl battery, through tloe Winninga of sind relay.the rmcirlle left lianrl elterneie conta-cib of relay' one; "lilleriglitlinnrl normal conieolg oiif *ro ground. ileays and 56170231 e 4,ian-- ergizerl lirongliou lie ilnrefion off' lire iinprilse e circuit isesefi'blielierl e'enilinille fe pole on? beifery 552 liroi C on'terrigiielianci alternate conact or reir-ry' the righi-hand alternareconoci of relayv 536i? Elie right-bend norrnel eonino' of relay 560?'lie lower a -rnete @ontzien loi relay 'ilie simpler: eonrliieliorsinelnflecl in line A extending bet-Ween onices Z sind Ya lie lowernormal ooneete of rele-ye C09 and 10, die miclcile normal conrac of'relay 411,' the lower normal Contact of relay 12, the Winrlings ol polarrelays 40B enl 402, "alle Wind,-

ing,Y oie. relay` 413, lie middle normal conteeof relay 419., the uppernormal contacte of vrelay? '4l-ll. fri() and 409, tlie Simplexoonrluctors incluflefl inline C extending between oflices Y ncl Z, theupper alternare Contact W le'b-lmnd normal Contact of relay 560, theleft-hand alternate eonaolv of relay 561 and the inner leftlinnd ali-ernate conrac'r of reliiy 553 to "fire posiive poi@ of limiter-jg Reloj;/il energizes in tliiff circuit. anal liereliy pi vente dieenergizziliion of either or 'ilie relays elli?, fiiOa elli enel el?.

rel e. jy

during *die transmission or i3-lne impulse from slice Y.

The errengli and direction flow' of 'curreni'` ilirongli elle circuit.above described is enen as io tense polar relefv #103 to close ireriglrt-liinrl conaact. A circui is rliereupon esielilielieil extending"from grounded lier ieri; ilirongli the rigliliianrl conaci or pole?relay and windings of relays ik sind i055 o ground ai: 'the conact ofrelay 08. lnzi- .nrcli es lie resieance il? is not included in iii?cirrziiit lioili relays Oei and 405 Will ne and 'velay 405 in closinglowernioi n ernmo courriel eer-:ililiel e an obvious energizing; circuitfor relay 71219, imi izliie laire relfiy having been already energizedand locked, @Lilie eeablislinient of ilie einer,YA nienrioneil circuirhaie no eiiiec' upon tire relajyn 'The energizetion of releys iO/l zine.05 eeielilielies en iinpnlee circuit extending; from positive pole ofbattery M8 'through i'lie n'iirlille alternare contacto relay 404;, the

norniol eoniiac of relay 302, the, winding?, oi polar releye 301 and30()` ehe Winding of relay; 303, ille upper normal contee?J of rele);E02? lie Sniglex condoe'rors included in line (l ir Kling lieween olloeeX and. Y., die impor :ilrernzre eonieot relay 04, A r nornml contact oflrelay #fOenfl lie i 'Mince 4F21 'to the negative pole of battery 4.918.Relay 303 enerflizefi in this eircni, enel establishes :in obviousenergizing eir'cnii *for y .le but *the operiiiion of this reilly here*no enen@ noon lie System at this time.

The streng-iii :rml direciion of flow of enr ren* in glie impiileevii-enit above described e 'io canse poliu- Bl ibo elo-Se ias uppercomme. A, circnit'ie lien este, lielierl exiieniling n,troni groundedloiiaerj; elirongjii the lower (bonifici, ofi polar relay 361 nnrl 'thewindings o'l' relays 530eanrl 2505 lo ground.. Since the resietnnce innoi; inelnciedwin 'this circriir relays and 30.3 born reenoirl ro illecurrent i'lo l'ing in this eircnit relay Sill again :in oluvioneeircnifi for relai" Si@ Yfliicli is already energized enr?. loolrrl lioSupply batrery io #Lilie filamento of .repeaters ller :infi '.lliieenergizeion o; l esreblielies n circuit extending; 'fron grounfleillmitery through rlie normal con were of' relaye 307 and 306, lie lowernir're conact orf reloj; S05 and the le Winding; or relev to groun.Relay energizes in this oircnitranrl es-nlilishes e. eircnit for relay202 enclingr from ground through the outer righi/henri alternate oontaeto'iE relay 253, the 'winding of releyQO, and elle normal conte :i ofrelay 2.93 ifronnflefl imiter): Reinv Q02 eneine-S disconnects polarrelays :unl 530i nml relay 203 from lie conrlncors included in liephysical lines at oiiice X. 'The energizeiioo mal contacts otlrelays-259 and 260, the upper alternate contact ot' relay 202, thesimplex conductors included in line C extending between Figs. 2 and 1,the upper normal contact of relay 4, the winding ot relay 5, thewindings ot' polar relays 2 and l, the lower normal Contact of relay 4,the simplex con ductors included in the'line. A extending be digs. 1 and2, the lower alternate contact of relay 202, the right-hand normalcontacts of relays 260'and 259, the inner letthand alternate contact otrelay 253 and the resistance 264 to the negative pole ot battery 262.Relay 3 energizes in this circuit and establishes an obvious circuit forrelay 14, but the operation ot this relay has no effect upon the systemat this time.

The strength and direction of flow of the. current in the impulsecircuit just described is such as to cause polar relay 1 to close. itslower contact whereupon a circuit will be established from groundedbattery through the lower contact of polar relay 1 and the windings ofrelays 5 and 6 to ground. Re-

.lays 5 and 6 energize owing to the 'tact that resistance 12 is notincluded in the circuit and the energization ot' relay 6 establishes acircuit for relay 10 extending t'rom grounded battery, through thenormal contacts of relays v8 and 7,' the alternate contact of relay 6and the lower winding of relay 10 to ground. Relay 10 energizes, butinasmuch as the relay 31 is now energized the upper winding ot relay 10is short circuited by the ground at the lett-hand alternate contact otrelay 31 and consequently relay 10 will only remain energized throughoutthe duration of the impulse and will not lock through its upper windingand contact. The energization of relay 10 establishes a circuit forrelay 35 extending trom grounded battery, through the winding ot' saidrelay, contact ot relay 10 and the lett-hand alternate contact of relay31 to ground. Relay 35 energizcs and throughout` the duration ot` theAimpulse connects a source otl signaling current 36 to the line and linkcircuit connected to jack 30. The operator at oflice 1V, having herlistening key actuated at this time. will receive a momentary audiblesignal `which will indicate that the operator at oliice Z has rcspondedby inserting a plug into l,..ck 530 and conversation may now proceedbetween the operators over the phantom line ll.

At the termination ot' the conversation over .line B the operator atoflice 1V may `transmit a disconnect signal to the operator at oiiice Z,or during conversation over line B, may rc-ring the latteroperator byactuating tiie ringing key ot' the link circuit connected to jack 30which will establish a circuit. extending from a source o1. signalingcurrent through the tip contacts of the plug ot' the link circuit andjack 30, thc lett-hand normal contact otl relay 35, the winding ot'relay 34, the left-hand winding ot' the repeating coil adjacentto relay31,'thc right-hand normal contact of relay 35, and the ring contacts oljack 30 `and plug T0 to ground at said ringing key.

llelay Il-L energizes and in closing its righthand contact shortcircuits the line B and therefore prevents the transmission ot thesignaling current through the repeating coil associated with said line.The energization ol. relay 31 establishes an impulse circuit extending'irom grounded battery, through the right-lnind alternate contact o1relay 31, the normal contact ot' relay 32 and the lett-hand contact oirelay 3l., where the circuit joins the previously described impulsecircuit tor relays 53 and 54. The impulse sending mechanisms at thevarious oflices now operate in the same manner as described inconnection with the initiation ot' a call on line B at office 1V withthe following exception: lVhen relay 509 encrgizes in response to theoperation ol marginal relay 505,7relay 531 being now energized, theupper winding of relay 509 is short circuited by the lground at. I

the right-hand alternate contact otrelay 531 and relay 509 thereforeonly remains energized throughout the duration of the impulse. Theenergization of relay 509 establishcs a circuit extending from groundedbattery, through the winding o'i relay 535, the contact ol relay 509 andthe right-hand alternate contact ot relay 531 to ground. Relay respondsto the current flowing through thi.-` circuit and connects the source otsignaling current 536 to the line B and the link circuit engaged by jack530 and this signaling current will operate relay T3 to light lamp T1.The operator responds by actuating the listening key T2 whichextinguishes lamp 711 and upon ascertaining that disconnection isdesired, withdraws the plug trom jack 530 and relays 531 and 533release. Release relay 533 has no effect upon the system at this timeassuming that relay 541 is still energized.

Likewise.Y the operator at oflice Z may` transmit a disconnect signal toor re-ring the operator at otiice X by the operation of the ringing keyof the link circuit engaged in jack 580. This will cause the energization. ot` relay 534. which in closing its lefthand contact shortcircuits the line B and tact ot` relay 534 where it joins vthe impulsecircuit previously vdescribed which extends its through the windings otrelays and 554-. rlhese relays operate as before to transmit the signaltrom oliice Z to oice Y where the same is repeated through to oliices Xand lll. Relay l0 is again :energized to cause the operation of relay 85in the same manner as previously described and the source ot signalingcurrent 36 is again con nected to the linlr` circuit engaged with iacl;h

30. lin the s e manner as preyiously set 'loi-tn, lamp Tl is lighted andextinguished and the operator withdraws the pluri from ila@ 'q l( J .tv:ioclh olpemifor at ofte@ lll initiates a cal? t0 07717:@ Z' other Zineground. Relay 7l energizes in this circuit but its operation has noeffect. Relays Lll and l2 energize in said circuit and relay ell locksthri'iugh its winding` and middle alternate Contact to ground. rl`heenergization ot relay ell opens the energizing; circuit for Arelay d2,but this relay being slow to release does not open its alternate contactuntil a suflicient time has elapsed tor the transmis sion oit theimpulse from o'liice lll. The energization ot relay 42 establishes acircuit extending 'trom grounded battery through the alternate Contactrelay 4t2, the lett hand winding;` of rel y la' nd "he winding otslow-to-release relay to `grourul. lie lays 55 and 56 energize and thelatter relay in closing its alternate contacts short fircuits relays 52.54: and 58 so as lo prcrent the operu ation oiC these relays during; thelirausni' oli-the impulse trom oflice lll. .lhe l E zation ot relay :'35establishes a circuit` tending trom grounded but throubli the normalcontact ot relay tl, windingl` ot relay l. the outer right-handalternate contact ol relay to gfrounijl. Relay energiwes to disconnectthe polar relays l and trom the simplex conductors connected to thephysical lines extending from oilice lll. The energization of relay alsoestablishes an energizing circuit tor relay extending: trom groundedbattery, through the winding oli relay 309. the middle right-handalternate contact olf relay the i nt-hand normal contact ot relayT 5land the normal contact of relay 53 to ground. lielay 60 is energized andrelay 55 also being); energized. an impulse circuit .is establishedextending Atrom the 'positive pole ot' lQO-yolt battery 63 through theouter left-hand alternate contact of relay 555 the lett-hand normalContact or" relay 59, ethe recaer@ middle alternate contact of rela7 60,lower alternate Contact ot relay il, the simplex conductors included inline il extending between Fig'. l and Fig. 2, the lower normal contactot' relay 202, the windings ot polar relays i201 and 5200, the winding'of relay Q03, the upper normal contact or relay the simplex conductorsincluded line C extending between llig. Q and llig. lf. the upperalternate Contact oft relay l, the -..ght--hand alternate contact otrelay 60, the right-hand normal contactant relay 59 and the iniicrleft-hand alternate contact ol" relay to the negative pole ol batteryThis impulse circuit maintained throughout the energi- Zation ot relayl2 and upon the release ot this relay. relays and 5G deenerlggjize. Theelease ot relay 4:2 establishes an energizing circuit for relay /llextending' trom grounded battery through the riglitdiand alternatecontact oit relay ell7 the normalcontact et relay 412, and the windings;of relay all to ground. The energizaton ol relay l?,- at this time hasno effect upon the sy tem assuming that relays 21j' 31 and L ll aie nowall energized.

rlhe current flowing' through the impulse circuit just described Venrises relay to establish an obifvious en cuit lor relay 2te., but theoperut is relay has no elect upon the sy r this time. The strength anddirection ot itlow ol cur .rent through polar relays 201 and 202 is suchas to cause both et the. polar relays to close their upper contacts. ilcircuit is then established 'extending from grounded battery. throughthe resistance Q12, the upper contact olAI rel 20L the windings otrelays i04- and E30.. l stance 212 being in the circuit, rc. y 12.05does not respond to the current flowing therein. 'Another circuitestablished from Igrounded battery, thi-outil; the resistance 21S-3. 1`upper contact ot "polar relay 200 and the windings oi relays 200 andQ0?. The relay 207, being` ,iarginale does not respond to the currentflowing in this circuit due to the resistance 52-13. rlheret'ore. relaysand 206 are now energized. A circuit is now established eX- teuding tromgrounded battery, through the normal contact ot relay 20T, the loweralterH nate contact ot relay and the lett-hand winding' of .relay 355 toground. Relay energizes to establish a circuit lfor relay U02 extendingvfrom ground through the middle right-hand 'alternate contact o'f relay355, winding, of relay 302 and the normal contact oiu relay 303 toground. Relay 302 energizes to disconnect polar relays 300 and'ol -z 'Lnu the physical lines at omce li.. 'lli .L tion ot relay 4355 alsoestablishes a circuit trom the simnlert conductors' included in vforrelay 360 extending trom 2erounded batt-y relay 355 to ground.'Relays302, 355 and 360 now bein energized, an impulse circuit is establis edextending from the negative pole of battery 363, through the outerleft-hand alternate contact of relay 355, the left-hand normal contactof relay 359, the left-hand alternate contact of relay 360, the loweralternate contact of relay 302, the simplex conductors included in lineA extending between office X and otlice Y, the lower normal contacts ofrelays 404, 405 and 406, the middle normal contact of' relay 407, thewindings ot polar relays 400 and 401, the winding of relay 408, theupper normal contact of relay 407, the middle normal `contact of relay406, the upper normal contacts of relays 405 and 404, the simplexconductors included in line C extending be tween office Y and office X,the 'upper alternate contact of relay 302, the right-hand alternatecontact of relay 360, the right hand normal contact of relay 359, andthe inner left-hand alternate contact of relay 355 to the positive poleof battery 368.

The current flowing in this circuit again energizes relay 408 to removeground l rom its contact t0 prevent the energization oi any ofthe relays404, 405, 406 and 407 during the transmission of this impulse. Thestrength. and 4direction ot tlow oi current in this circuitis such as tocause polar relays 400 and .401 to close their left-hand contacts. Acircuit is then established 'from grounded battery through theresistance 41--1- andthe windings ot relays 4.11 and 412 to ground atthe relay 413. Relay 41'1. being marginal, does not energize but relay412 operates to close its alternate contacts. Air other circuit isestablished from grounded battery through 'the resistance 415 and thewindings of relays 400 and 410 to ground at the relay 413. Relay 409being marginal, does not respond to the current flowing in this circuit,but relay 410 encrgizes. A condition then exists wherein relays 410 and412 are energized and ground at the uppermost alternate contact of relay410 and at the middle upper alternate contact ol relay 412 is connectedto relay 419, but, as before explained, this relay is energized andlocked and the new circuit therefore has no effect thereupon. Thecnergization of relays 41.) and 412 establishes a circuit extendingrfrom the positive pole of battery 418, tbe lower alternate contact ofrelay 410. the lower normal contact of relay 409, the simplex conductors included in line A extending bevtween otlice Y and oflice Z, thelower normal Contact of relay 502, the windings of pola'.`

relays 501 and 500, the winding of relay 503, the upper normal contactof relay 502,

A the simplex conductors included in line C exouter upper alternatecontact of relay 412 n to the negative pole of battery 418. clay 503 isenergized in this circuit to again establish an energizing circuit forrelay 511. but the encrgization of the latter relay has no effect uponthe system at this time. Polar relays 500 and 501 both respond to Athecurrcnt tlowing in this circuit 't'rom battery 418 and operate to closetheir upper contacts. -i circuit is then established from groundedbattery through resistance 512. the upper contact ot' polar relay 501and the windings of relays 504 and 505 to ground. Relay 505 does notenergize in this circuit but relay' 504 operates'to close its contact.Another circuit is established from grounded battery through resistance513, the upper contact of polar relay 500 and the windings ol relaysy506 and 507 to ground. Relay 507.y being marginal, does not energize inthis circuit but relay 506 operates to close its alternate contactwhereupon a cricuit is established Jfrom grounded battery through thecontact ofi-clay 507, the alternate contact of relay 500 and the lowerwinding ot relay 510.to ground. It will be obvious that thc energizationoi relay 504 has no el'ect upon relay 508 since the energizing circuitpreviously traced tor this relay is opened at the normal contact olrelay 50G. in the circuit traced therefor and locks from ground throughthe winding and contact of said relay and the middle leit-hand normalcontact of relay 541 to grounded battery. The energizatiou ol relay 510establishes a circuit extending from ground through the lamp 51'0, thcright-hand normal contact ol' relay 5421 and the contact of relay 510 tegrounded battery at the inner left-hand normal contact olx relay 541.Lamp 510 is lightcd in this circuit and the operaio:- .it ollce Zobserving the lighted condition oi the lamp inserts the plug of anotherlink circuit into the `pick 540.

The engagement of a plug with jaclt 540 establishes an energizingcircuit for relays 541 and 542 extending from .grounded battery at thelink circuit, through the winding oi' relay 71, the sleeve contacts ot'the plug and jaclc 540, the winding and inner lctthand normal contact ofrelay 541 and the winding` o'l` relay 542 to ground. The energization,of relay 541 opens the circuit for lamp 510 and also breaks theenergizing circuit for relay 542. The latter relay being slow to releasedoes not open its alternate contact until a sutlicient time has elapsedto transmit a signaling impulse from oflice Z. The circuit for thisimpulse now extends.. from grounded battery, through the alternatecontact of relay 542, the right-hand winding of relay and the Windingoi' .slow-to-release relay 556 to ground. The energization of the latterrelay establishes, through its alternate contacts, short c1rcu1ts Relay510 cnergizcs 9 rent in the impulse circuit just ground, 2()

pulse through office l.

. relays 404 flrom `rounded batteri! :y o, thewinding ot' relay 502 andthe outer left-h and alternate Contact of relay to ground. llelay 502energizes and as betere disconnects polar relays 500 and 50i from theconductors included in the physical lines at volice' Z. The energizationof'relay also establishes a circuit for relay 560 'eatend'ug fromgrounded battery throu ah the i ff said relay, the inidcontact oil relay555, nal'contaet of 'relay 551 the leithand non and Y Relays and 500 nowbeing` energized, an impulse circuit is established extending trom thepositive: pole out battery 503, through the outer ruht-hand alternatecontact ot relay Hbhthand'normal 559, l'the niddle alternate contact otre au 58 the lower alternate con tact ot' relay 502, the impleirconductors included in line it.; ending. between olhces Z mi', the lower#mal contacts ot relays and i 409 and 4l0, the middlenormal Contact o'trelay 411, the lower normal Contact of relay 412, the wi ndinrfs ofoolar relays 403 and i J i 40:2 ie i ol-x relay vthe middle normal eo'tot or is i122, the upper normal conta s ot relays 411, 410 and 409, thesimpler; conductors included in line C en# tending between otlices Y andZ, the upper alternate coi ot relay 502, the lett-hand alter conta y ovlay 500, the. lett-hand normal Contrat ot relay 559, and the innerright-hand alternate 'contact ot relay v555to the negative pole ofbattery 5655. ltelay 413 is energized in this circuit and removes groundfrom its Contact to prevent the energization oi any ot the relays 409,410, 411 and 4t2 during the transmission ot the im- At the terminationpulse at otlice Z, relay ot 'the il. 542 releases and establishes anenergizing circuit for re.- lay 543 extending through the normal contact ot relay 549l and the left-hand alternate contact of relay 541. l'lhest-rength and direction 'of flow of curdescrihed is such as tocause-the polar relays 402 and 403 to close their let^-liand contacts.circuit is then established through the resistance 41T, the left-handcontact or polar relay 403, the windings of and 405 and the Contact ofrelay 408 to ground. Relay 404, being marginal, does notA respond to thecurrent flowing through this circuit, but relay 405 operates.Anothercircuit is established extending 'throu gli thev resistance416,1the lett-hand Contact ot polar rerelay 555, es-V the i'iorinalContact of relay to from grounded battery,4

lay 402 and the windings ot relays 406 and 40?'110 ground .at theContact ot relay 408. llelay 40S, being marginal, does not energize inthis circuit, but relay 407 operates. A condition now exists in whichrelays 405 and 407 are operated, hence an impulse circuit is establishedentending lfrom the positive pole oi battery 418, through the upperalternate Contact of relay 405,.the 'upper'norrnal contact oit relay404, the simplex conductors included in line 'C extending betweenoliices Y and X., the upper normal Contact ot relay 302, the winding ofrelay 303, the windings ot polar relays 300 and 301, the lower normalContact of relay 302, the simplex conductors included in line Aexten-ding be tween otlices X and Y, the lower normal (5on-V tact/ol2relay 404, ,the inner lower alternate Contact o't relay 405 and thelowerinost alten of battery 418.

Relay 303 responds to the current flowing through the above describedimpulse cireuit and'in operating establishes an energizing circuit 'forrelayv 314, but 'the' operation of this relay has no effect upon thesystem at this time. rllhe strength and direction ot the llow otcurrentthrough said impulse circuit is such as to cause polar relays 300and 301 to close their lower contaets.' lObvious circuits are nowestablished for relays 304, 305, 806 and 307 through resistances 312 and313. Relays 305 and 307,'being marginal, do not operate in said circuitsIdue to the inclusion ol said resistance therein. The operation ot relay306 establishes a circuit extending from grounded battery, through thenormal contact of relay 307, the lower alternate contact ot relay 306and the right-hand winding oit relay'255 to ground. Relay 255' energizesand establishes an obvious circuit through its middle left-handalternate contact Jfor relay 202 'which operates and disconnects polarrelays 200 and 201 trom the conductors inyeluded in the physical linesat otiice X. The

Yeluded in line A extending between Figs. 2

and 1, the lower normal Contact ot relay 4, the windings ot polar relays1 and 2 and relay 3, the upper normal .Contact ot relay 4, the simplexconductors included in 4line C extending between Figs. l and 2, the. up.

per alternate Contact of Yrelay 202, the 'let rio hand alternate contactof lrelay 260, the lefthand normal contact ot' relay 261 andthe innerright-hand aiternvtecontact of relay 255 to the negative i. battery 263.5 Relay 3 energizes inf-tbe circuit just described and again establishesthe energizing circuit for relay 14, the operation of which has noeti'ect upon the system at this time. The strength and direction of flowot the 'current in the impulse circuit just described causes polarrelays 1 and 2 to close their upper contacts. Obvious circuits arethereby closed through resistances 12 and '13 for relays, 6 7 and 8, butrelays 6 and 8,.being l5 marginal, do not respond to the current flowingtherethrough. The'operation ot relay 7 establishes a circuit extendingfrom grounded battery through the normal contact ot relay 8,. thealternate contact ot' relay 7 and 2.0 the lower Winding of relay Yl1 toground. Relay 11 energizes, but does not lock through its upper windingand contact since relay 41 is noW operated and ground is connected tothe lett-hand alternate contact thereot` to shunt said upper winding.The energization of relay 11 however, closes'a circuit extending t'romgrounded battery through the Winding of relay 45, the contact of relay1l and the left-hand alternate contact of relay- 41 to ground. Theenergization ofi relay 45 'connects a source of signalingv current 46 tothe link'circuit engaged lwith jack 4l) and the operator at oiice lVreceives an audible signal which lasts throughout the energization o't'relays 11 and 45.

At the termination ot the conversation over line C, the operator atoflice lV may transmit a disconnect signal to the operator at office Zor sheI may re-ring the latter op- 40 erator during conversation byoperating the ringing key otl the link circuit connected with jack 4Qand thereby cause the energization of relay 44 through an obviouscircuit. Relay 44 in closing its right-hand contact 45 short circuitsthe line yC and prevents the transmission of the signaling impulsethereover to oiiice Y. The closure of the letthand contact of relay 44establishes an impulse circuit extending from grounded battery throughthe right-hand alternate contact of relay 41, the normal contact ofrelay 42,'and the left-hand contact of relay 44 Where it joins thecircuit previously described fer relays and '56. These latter relaysoperate as previously set 'forth yto cause the transmission of animpulse through the various otiices to operate relay 510.' The o erationof relay 510 results in the connection of the source of signalingcurrent 546 to the linkcircuit engaged with jack 540 to light the lampT4 in the same manner as described in connection with the applicationot' signaling current to lines A an B. The operator` at ofiice Zanswering 55 the signal, then listens in. on hue and if 4circuit isestablished extending from ground- Iot the link circuit connected withjack 540 whichcauses the energization of relay 544. Lilie (l is againshort-circuited by the energization ot' relay 544. and an impulsecircuit is established extending trom grounded battery, through thelett-hand alternate contact ol relay 541, the normal contact ol relay542 and the right-hand contact ot relay 544 S0 where it `joins thepreviously described energizing circuit 'for relays 551 and 552?. Animpulsc is consequently transmitted from olicc Z through the otherolliccs to again'encrgize relay ll, which results in the application ofsignaling current .from the source 46 to the link circuit connected withjack 4() in the saine manner as previously described to light the lampT4. The operator at otlice W then removes the plug from jack 4 0 causing90 relays 4 1 and 43 to release.

[restoration of 'repeaters when all Zines are idle.

A t the termination ot' the call on line C in 9o the instance where theoperator at oliice \V transmits a disconnect signal to ollice Z and thenremoves the plug from jack 40 to rca lease relays 4l and 43, assumingthat the other lines are idle, thc following operation takes place torestore the telephone 'repeaters to normal.

vUpon the release of relay 4l. an impulse i ce ed battery through thecontact of relay 43, m5

this relay being slow to release. the outer right-hand norn.al contactsof relays 2l, Ill and 41 in series. the right-hand winding of relay 5Tand the winding ol slow-to-releasc relay 58 to ground. Relays 5T and 5Sener,- gizc and the latter relay in closing its alternate contacts shortcircuits thc windings oi' the other slow-to-rcleasc relays 54 and 5G andprevents operation ol these relays should another impulse be started atoflice lV simultaneously with the impulst` utilized to restore therepeaters.' The cncrgization of relay 5T establishes a circuit extended`from grounded battery through the normal contact of relay 3, thcwinding of relay 4, and the outermost U0 lett-hand alternate contact ofrelay 57. to ground. Relay 4 energizes and disconnects polar relays land Q and relay 3 from the conductors included in the physical lines atoflice W. The encrgization ot relay 5T also 125 establishes a circuitextending from groul1ded batteryr through the winding ot' relay 59,

the next to the innermost left-hand alternate contact ot' relay 5T. andthe right-hand normal contact of relay 56, to ground. Another the nextto the outermost leletfhand alten nate contact or relay to ground,Relays 802, 35'?, 359 and 360now being cirier'gized7 an impulse circuitvis established extending iergiaation of ending1 A.Jorn grounded battery1 the Winding` el relay 00, the next 'to e ou rriost left-hand alternateContact of i3 .l y li?, the righthand normal Contact el frein thenegative pole of lbattery 363 70 elay il and the normal Contact of relay53 through the outer riqlithand alternate con sund. Relays und 00energize in the tact or relay 357, 'tue right-hand alternate circuitstherefor and the energicontacts of relays 359 and 800, the upper serelays establishes an impulse alternate Contact of relay 302,the'sinrplex xlding freni the positive pole of conductors included inline @extending be- ,J irough the' outer righthand altween ollices K andY, the upper normal contact of relay 57, the righthand contacts orrelays 40e and 405 and middlea contacts ot relays and 00, the normalcontact of relay 4061, the upper norte contact o t relay l, the siinmalcontact ol relay 407, the Winding. of re- "P led in line il extendingVlay 00, the windings or polar relays L01 and 8U 1 and 2, 'the uppernormal con- 1l00, the' middle normal contact or relay e0?, l/ the,'windings or relay Q03 thelower normal contacts of relays 406, 405 'el'00 and 00L, the lower norand 404,'the simplex conductors included inrelD the simplen; conline A, extending between offices and K, orsincluled'in nue nl extending` between the low-er alternatel contact ofrelay 302, the 85y 1 fl e lower alternate contat .of lett-hand alternatecontacts of relays 360 and idele alternate contact ol relay 359, and theinner righthand yalternate con-- nandal' ate Contact ol" relay tact volirelay 357 to the positive pole oit bat-v light-hand alternate cont 363.y i y "c the negative pole of biit- 'lelay 08 energizes in the circuitjust de '90 v scribed and removes ground 'lrorn its conen iS Ciffllllkwil 'to prevent the energization of any of es an obriou seizing circuitigor 7e 404, 405, 406 md 407 during the release "uit the operau `sionoit the impulse through oce i no eilett 'strength and direction or lflowof 95 'igt and direc: it through the. impulse circuit inst the iinpfubec is such as to cause polar relays and 401 to close their riglr-t-handcon tacts. @ne circuit is thereby established ein sin@ circ-,uit iL,neleupon e l ten tj troni grounded battery through the'lO iiicledbattery l'irough I ri 'n `.aand contact of polar relay v400, the

solar r y i201 and the vWindios-'s windings oit relays T09 and 410 andtheeonto ground, and lioth tact of relay @L13 vto ground. linasrnuoh asrelays ener ize in this circuit. 'the resistance i155 is not included inthis ciri f circuit is established troni gioundcuit, relays lL-09 andlil-10 will both energize. 1405.

Another circuit is established extending; r .i lay 200 and thc windingsot relays lli-oni grounded battery through the right- 1 d 307 t()ground, whereupon both ot rs ene ze. 'The energization of hand Contactor polar relay 401 and vthe windings of relays lll and 412 t0 gro-und,

tive pole of battery 4,18 through the middle alternate contact of relay409, simplex conductors included inline C extending between offices Yand' Z, the upper. normal contact of,

207 estabielies a circuit extending' at the contact olf relay lidlRelays L11 andllO i'rorn grounded battery through the altei'- 412 bothenergize'in this circuit to establish :o 'Le contact of relay 20T andthe right-handv a circuit 'for relay Ll20 extending from Windin ol relay557 vto ground. Relay grounded battery through 'the Winding of `ined andcloses a circuit tor relay said relay, the lower alternate 'contact ofla e ,riding 'from grounded battery relay 419;, the upper alternateyContact of 11,5 thro the normal Contact or' relay 303, relay lll, theiniddle mpper alternate Con- 'Winding of relay/202 and the next to tactoiA relay -lll), and the kupper alternate lost lett-hand alternateContact of contact of relay 409 to ground. RelayllQO TK-to ground. Relay302 energizes energizes in this circuit and in so doing cennects thepolar relays 300 and opens the locking circuit for relay 419 which l()4A and (l `at office Y. The energization l v relay 502, the winding ofrelay 503, the windings of polar relays 500 and 501, the lower normalcontact of relay 502, the simplex conductors included in line A extendmgbetween oiices Z and Y and the lower alternate contacts of relays .409and 411 to ne ative pole of battery 418.

included in these circuits, f 505, 506 and l leased.

the transmission of the elay 503 energizes in this circuit andestablishes an Obvious circuit ior slowtorelease relay 514, but theoperation ot' this relay at this time has no eii'ect upon the system.The strength and direction'ot flow of the impulse circuit just describedcauses the energization of polar relays 500 'and 501 and the closure oftheir lower contacts. Une circuit is `thereby established extending fromgrounded battery through the lower contact of polar relay 501 and thewindings of relays 504 and 505. Another circuit is established fromgrounded battery through the lower contact ot' polar relay 500 and thewindings o relays 506 and 507 to ground. Since the resistances 512 and513 are not the relays 504, 507 are energized and the energization ofthe latter relay disconnects the battery from the normal contact thereofso that neither of the relays 508, 509 or 510 will be energized andconsequently no signaling impulse will be transmitted to the operator atoffice Z.

, y Upon the removal ot' the plug from jack 540 at office Z in responseto the disconnect signal transmitted by the operator at otlice W overline C, relays 541I and 543 are re- Relay 543 being slow to-releaseestablishes anl impulse circuit upon the restoration ot' relay 541 whichextends from grounded battery throughy the contact of relay 543, theouter left-hand normal contacts of relays 521, 531 and 541 in series,

the left-hand winding of relay 557 and the winding of relay 558 toground. Relays 557 and energize and the latter relay in closing itsalternate contacts shunts thel windings oi' relays 552, 554 and 556 toprevent the operation of these relays during impulse from office Z.' Theenergization of relay 557establishes a circuit for relay 502 extendingfrom grounded battery through the normal contact of relay 503, thewinding of relay 502 and the outermost right-hand alternate con tactyof, relay 557 yto ground. energizes and disconnects the polar relays500 and 501 from the conductors included in the physical lines at oliceZ. The energization of relay 557 also establishes a circuit for relay559 extending from grounded battery through the winding o't` said relay,the next to the innermost right-hand alternate contact of relay557 andthe left-hand normal contact of relay 556 to ground. A

.circuit for relay 560 is also established by the operation of relay 557extending from Relay 502 grounded battery through the winding of relay560, the next to the outer-most righthand alternate contact oi relay557, the lefthand normal contact of relay 551 and the normal contact ofrelay 553 to ground. Re lays 502, 559 and 560 being energized, animpulse circuit is established 'extending from the positive )ole o'tbattery 56 through the outer leit-hand alternate contact of relay 557,the lett-hand 'alternate contacts ot' relays and 560, the upperalternate contact ot' relay 502, simplex'conductors included in linev (lextending be tween oflices Z and, Y. the upper normal con- .tacts ofrelays 409, 410 and 411, the middle` normal contact ot'- relay 412, thewindingr ol relay 413, the windings of polar relays 402 and 403, the lay412, the middle normal contact of relay 411, the lower normal contactso1 relays 410 and 409, simplex conductors included in line A extendingbetween ofiices Y and Z, the

lower alternate contact of relay 502, the

lower normal contact of remiddle alternate contact of relay 560, the

thereby established from grounded batterythrough the right-hand contactsof polar relays 402 and 403 and the. windings of relays 404, 405, 406and 407 to ground at the Contact ot' relay 408. Relays 404, 405, 406 and407 energize in these circuits to again. cause the operation of relay420, but this operation of said relay has no effect upon the system,since relay 419 has already been released to disconnect the battery fromthe telephone repeaters lat oflice Y. The energization of relays 404,405, 406 and 407, however, establishes an impulse circuit extending fromthe positive pole of battery 418 through the middle alternate contact ofrelay 404, the simplex conductors included in line A extending betweenoffices Y and X, the lower normal contact of relay 302, the windings ofpolar relays 301 and 300 and relay 303, the upper normal contact of re`406 to the negative pole of batthis circuit and establishes an en-

